Novelist Mark Haddon has picked up his second book prize in a month for The Curious Incident of the Dog in the Night-Time.
Haddon did not write the book for teenagers
The book, written through the eyes of an autistic 15-year-old, picked up the inaugural Booktrust Teenage Prize.
Shortlisted books included Lynn Reid Banks' The Dungeon, Melvis Burgess for Doing It and Lucas by Kevin Brooks.
Haddon recently won the Guardian Children's Fiction Prize and featured on the Booker Prize longlist.
Haddon's book is about an autistic teenager, Christopher Boone, who, obsessed with Sherlock Holmes, sets out to investigate the death of a neighbour's dog.
Although winner of two children's book prizes, Haddon said he did not intentionally set out to write a book for children, pitching it more at adult readers.
But The Curious Incident of the Dog in the Night-Time has been a huge hit with readers of all ages.
The judging panel for the Teenage Book Prize included actress Julie Fernandez and writer Catherine Johnson, who were joined by three young readers.
Haddon picked up his £1,500 prize money and trophy at a ceremony in London attended by all the shortlisted authors.